There are several circumstances in which it may be desirable to monitor a person's physical activity. Athletes, the elderly, patients, mountaineers, are but a few examples of persons who may benefit or desire monitoring of their physical activity levels. An activity monitor may include sensors for monitoring physical movement of a person such as accelerometers, magnetometers, pressure sensors, altimeters, velocity sensors, angular velocity sensors, and gyroscopes, for example. An activity monitor may also include a sensor for monitoring physiological parameters, such as temperature, heart rate, blood pressure, electrocardiogram (ECG), and/or enabling other sensing functions.